Guys, i subscribed iTunes Match a month ago and i'm very happy with this service. I have all my music ripped and transcode in mp3 (vbr) except for a folder, the MISC one. In there, i put during the years lots of single mp3 songs that are very old and the quality is so bad (128,160....). So, i maybe can delete the song and redownload the AAC version of it but i was thinking: is this a true AAC version or maybe a bad transcode? I want to say, how the hell iTunes in maybe 10 second can find, download the high quality song to your mac and maintain the same name and tags? It's not strange? Did some of you made some quality test?

I'm afraid to delete all these songs and discover maybe that iTunes return me shit** version.

OP: You will easily be able to tell if iTunes returned "the shit** version." If you look at "iCloud Status," as in this illustration, it will tell you a track is "Uploaded" rather than "Matched."

This *usually* happens in cases where there are multiple masters of the album you uploaded and iTunes only has one.

The matched music you get is the same as that which they sell. It saves them from having to store tons of everyone's music files on their servers. The more they can match the better...presumably.

For me, it normally just matches everything. Especially so with newer music.

Edit: you can also ⌘-I on the song and look at the Summary tab. Under "Kind" it will say "Matched AAC audio file" if it is the matched audio file currently on your computer. You have to actually download the iTunes version first in this case. If it was not matched, or it was matched but you still have the original file, it will just describe the original file.